As computer networks evolve and grow larger, there is an increased possibility that address spaces will overlap between networks operating under the same protocol that seek to communicate with each other across a common backbone network. For clarity of discussion, the protocol operating in the networks seeking to communicate across the backbone will be referred to herein as protocol X. The Network Layer protocol operating in the backbone network will be referred to as protocol Y, which may be the same as protocol X. In general, it is desirable to allow some protocol X networks to communicate with each other across the protocol Y backbone network. On the other hand, it is well-known that it is not necessarily desirable to allow all the separate protocol X networks to merge together (i.e., communicate with one another), for one or more reasons. These reasons include network security and administrative considerations.
Another important reason for preventing communication between two given protocol X networks is the possibility of overlapping address spaces between the two networks. In some cases, overlapping address space occurs because addresses have been assigned in a non-coordinated manner across all the protocol X networks. One known solution to the problem of overlapping address spaces resulting from non-coordinated assignment of addresses is to change the addresses in one of the networks so that they do not conflict with the addresses of the other network. A more difficult situation involving overlapping address spaces arises when the overlap is necessitated because protocol X has such a small address space that it is an impossibility to assign unique addresses to the total number of nodes in all the separate protocol X networks. A method of merging protocol X networks having overlapping address spaces across a common backbone network regardless of the reason for the overlap is desirable.